I only get the error mentioned by you if I try to validate signatures using ECC.

When verifying a signature using with PSS padding the signature is verified as invalid. The reason than would be the use of an unknown format in digital signature. So the pss padding could be the unknown format.

The current draft of the ISO 32000-2 standard, which Acrobat implements, only supports a limited set of ECC curves – so make sure that you are using a support curve type.

In addition, PSS/RSAPSS padding is also not currently supported by the standard – however that is something currently being discussed for addition before the finalization of PDF 2.0 – so hopefully it will make it. But, at this time, since it is not part of the standard, Acrobat doesn’t support it.

Remember, Adobe doesn’t own PDF anymore (and hasn’t since 2007). All decisions are made by the ISO committee (which is FREE for anyone to join & participate!)

thanks so much for your answer. And yes I have read that it will be probably added in PDF 2.0. But is there already a date when PDF 2.0 will be released?

Is there a list or a paper with all supported elliptic curves supported in ISO 32000? In PDF 32000:1-2008 you wont find any hint about that. But the paper refers to RFC 2315, PKCS #7: Cryptographic Message Syntax, which does not refer to ECC indeed.

But besides the fact that most of the decissions are now made by the ISO committee unfortunatly we as a manufacturer of software for digital signatures have to follow the requirements and specification for that. So unfortunately some trustcenter and companies offer smartcards which are using ECC as signature algorithm. So we are facing more and more of the questions why Adobe Acrobat ends up in the mentioned error. Also PSS-Padding is recommended to replace the old padding scheme PKCS#1 v1.5. This recommendation took place in the RFC 3447 for RSA Cryptography Specifications Version 2.1 in year 2003.

No official date for PDF 2.0 at this time. The committee is hopeful to complete the work and achieve ratification by end of 2016, early 2017.

ISO 32000-1 does not support ECC at all. PDF 2.0 supports a limited set of curves, which are fully documented there.

It is unfortunate the there has been a disconnect between the crypto community and the PDF community – but each clearly have different goals – especially since PDF is concerned about ensuring that technology choices aren’t just “the choice of the day” but are really things that have been seen to already “withstand the test of time” and should be incorporated.